Yarn compacting apparatus

ABSTRACT

A fluid yarn processing jet having a yarn processing passage at least one conduit for supplying fluid thereto, the conduit being flared at the point of juncture with the passage.

United States Patent [191 Lloyd et al. 1 Aug. 7, 1973 [54] YARN COMPACTING APPARATUS 3,388,442 6/1968 Shuma ker 28/l.4 [751 Neil Lloyd; Archibald Owen. 3132??? 131323 53223551331313:113..........:':'aa;ff'l

both of Rock Hill, S.C.; David C. Brenner, Shelby, N.C.

[73] Assignee: Celanese Corporation, New York, gi g l, i ggj gy W v Attorney-Thomas J. Morgan, Stephen D. Murphy 221 Filed: June so, 1971 and when Blanke [21] Appl. No.: 158,326

[57] ABSTRACT [52] US. Cl. ..28/1.4 [51] Int. Cl. D023 1/16 [58] Field of Search 2s/1.4, 72.12; A yam Pwcessmg J havmg Y Pwcessmg 57/34 B passage at least one conduit for supplying fluid thereto, the conduit being flared at the point of juncture with [56] References Cited the Passage- UNITED STATES PATENTS v 3,125,793 3/1964 Gonsalves 28/14 10 Claims, 7 Drawing Figures PATENTEUMJB 1W 3.750.242

2* FIG. I

INVENTORS NEIL E. LLOYD ARCHIBALD A. OWEN DAVID C. BRENNER ATTORNEY PATENIEB AUG 7 I975 3 f 5f) 24-2 SHEET 8 8F 2 Fig.4 Fig.5

PRIOR ART PRIOR ART INVENTORS NEIL E. LLOYD ARCHIBALD A. OWEN DAVID C. BRENNER BY A ATTORNEY l YARN COMPACTING APPARATUS This invention relates to fluid intermingling jets for multifilament yarn, and more specifically, to fluid intermingling jets employing supersonic filled velocities.

Yarn producers have long sought efficient methods for processing multifilament yarns so as to either bulk these yarns or find a substitute for twisting operations.

It is well known in the textile industry that continuous filament yarn bundles in their as spun or zero twist configurations perform poorly in many of the common textile operations such as winding, weaving, knitting and the like, primarily due to a looseness of structure that permits individual filaments to snap and break, thus forming fluff balls, slubs, ringers, wraps, strip backs or similar defects. Zero twist yarns also have a tendency to run in the form of a ribbon over guides, rollers and so forth, whereby as a result of increased frictional contact, the yarns are more readily abraded and subject to breakage. As a result of these shortcomings, continuous filament producers usually carry out the additional step of twisting each continuous filament yarn bundle to provide an acceptable starting product in fabric weaving and knitting operations. The twisting operation serves to compact and unify the yarn bundle, thus resulting in a more cohesive structure which resists the pulling out of individual filaments. The twisting operation however, is expensive and time consuming and does not lend itself to the continuous operation which characterizes much of the manufacturing sequence in the preparation of the zero twist continuous filament yarn bundle.

It is also well known in the textile industry that a multifilament yarn bundle can be crimped by setting the yarn in a distorted configuration. However, mechanical means commonly employed for achieving the distorted configuration are time-consuming and usually have limited processing speeds inasmuch as moving parts or heavy frictional drag are often required. Such methods may also result in adverse effects on physical properties of the yarn such as reduced elongation and tenacity, and fiber damage.

In order to overcome the expense of the twisting operation, and also to employ a twist substitute manufacturing operation which is adaptable to the continuous filament yarn bundles, compact interlaced yarns have recently been introduced in the textile industry. Compacted interlaced multifilament textile yarns of the type presently under discussion are set forth in US. Pat. No.

2,985,995. In brief, the compact interlaced multifila ment textile yarns of the prior art are produced by subjecting an as spun substantially zero twist continuous filament bundle to the action of one or more fluid jets whereby individual filaments are randomly intermingled with adjacent filaments and groups of filaments discussion are set forth in US. Pat. No. 2,852,906. In brief, the fluid bulked continuous filament textile yarns of the prior art are produced by subjecting a continuous filament yarn to a fluid stream jetted rapidly from a confined space to form a turbulent region. Yarn to be treated is fed into the path of the moving fluid stream so that the yarn is interacted with it and the individual filaments are separated from each other and whipped about violently in the turbulent region. The violent action produces convolutions in the yarns that are retained during withdrawal, winding and further processing.

Inasmuch as the primary reason for the acceptance of fluid bulking and compaction techniques by the textile industry is one of economics, the criteria for use of a particular type of apparatus for achieving multifilament yarn compaction is based on intermingling efficiency and fluid consumption rate. It can be readily seen that in order for a multifilament yarn to be satisfactory for those textile treating operations to which yarns are normally subjected, a satisfactory degree of intermingling or compaction must be achieved, efficiencies in yarn processing operations usually being directly correlatable to compaction levels. However, inasmuch as twist substitute techniques are applied for economic reasons, the air or other compacting fluid consumption must be sufficiently low to produce a product, the cost of which is substantially lower than twisted or mechanically bulked yarns.

The value of supersonic fluid velocities in effecting compaction and/or bulking of continuous filament yarn bundles is recognized in US. Pat. No. 3,525,134. The aforementioned patent discloses apparatus employing fluid entry ports of constant cross-section for supplying fluid to a yarn processing bore having a throat region and a continuously expanding treatment chamber. The yarn processing bore, rather than the air entry ports are designed so as to achieve high fluid velocities.

along the length of the yarn to maintain the unity of the In accordance with this invention, it has now been discovered that a highly efficient yarn intermingling or bulking apparatus is achieved by a design wherein a yarn processing bore has at least one fluid entry port disposed therein, the fluid entry port being initially of constant cross-section and diverging to maximum area at the point of juncture with the yarn processing bore where at supersonic fluid velocities are caused to occur at the point where the diverging section of the fluid conduit exhausts into the yarn processing bore. The fluid must be a compressible fluid such as air, steam, nitrogen, carbon dioxide and the like and may be preheated or precooled. If an intermingling apparatus intended to compact multifilament yarn, is desired, the yarn processing bore is preferably of constant crosssection.

It should be understood that the fluid entry port may have any geometrical three-dimensional cross-section along its length with the area of minimum cross-section constituting the "throat." The fluid entry port, or ports, may contact the yarn processing bore either radially or tangentially or at any angle intermediate these positions, and may be in a plane which is perpendicular to, or at an angle to, the longitudinal axis of the yarn processing bore.

A better understanding of one form of the invention may be had from the drawings wherein:

FIG. 1 is a side view of one form of the apparatus of the invention;

FIG. 2 is a front elevation cross-sectional view of FIG. 1 taken along the line 2,2;

FIG. 3 is an isometric projection of FIGS. 1 and 2;

FIG. 4 is a photograph of an air entry port of this invention operating at 140 pounds per square inch gauge air pressure;

FIG. is a photograph of a prior art air entry port operating at 140 pounds per square inch gauge air pressure;

FIG. 6 is a photograph of an air entry port of this invention operating at 160 pounds per square inch gauge air pressure;

FIG. 7 is a photograph of a prior art air entry port operating at l60 pounds per square inch gauge air pressure.

Turning to FIG. 1, a body member 1 is provided with a yarn processing bore 2 shown in phantom, yarn processing bore 2 having a constant diameter along its entire length. Air entry ports 3 and 4 are disposed on opposite sides of block member 1, air entry port 4 being shown in phantom view. Circular depressions 5 and 6 are provided in block member 1 for receiving 0 rings which permit an effective seal to be made between an air line (not illustrated) and block member 1 for supplying air or other fluids to fluid entry ports 3 and 4. The geometry of the fluid entry ports 3 and 4 are more readily ascertainable from FIG. 2 of the drawings. For ease of fabrication, fluid entry ports 3 and 4 are disposed in inserts 7 and 8 respectively, which in turn are received by orifices in body member 1, whereby portions 9 and 10 of fluid entry ports 3 and 4 respectively may be easily machined prior to assembly inserts 7 and 8 in block member 1. As can be seen in FIG. 2, fluid entry ports 3 and 4 are radially disposed with reference to yarn processing bore 2 as can be seen in FIG. 1 of the drawings. Fluid entry ports 3 and 4 lie in a plane which is perpendicular to the longitudinal axis of yarn processing bore 2. Completing the assembly of body member 1 is yarn string-up slot 11 which for convenience has a V-shaped notch disposed in advance of the slot which is radial to yarn processing bore 2 and intermediate fluid entry ports 3 and 4.

As can be seen in FIG. 2, the fluid entry ports 3 and 4 have a minimum diameter which will be referred to as throat and maximum diameter which will be referred to as the exhaust end. When the apparatus illustrated in FIGS. 1 to 3 of the drawings are operated at air pressures of 80 to [60 pounds per square inch gauge, the following results are obtained:

of 0.04! inches and a yarn passage 0.093 inches in diameter to compact 150 denier 40 filament bright acetate yarn employing air pressures of 160 pounds per square inch gauge, average compaction values of 0.29 centimeters were obtained. The compaction value was obtained according to the procedure set forth in US Pat. No. 2,985,995.

The apparatus of this invention may be studied by means of the Schlieren method wherein density gradients can be observed and measured. This system of observation and measurement depends on the phenomenom that light passing through a density gradient in a gas is deflected in the same manner as though it were passing through a prism. In high-speed gas flow the density changes may be sufficiently large to make those phenomena sizable enough for optical observation, depending upon velocity gradients that generate the density changes. In properly designed fluid nozzles, supersonic fluid velocities may be generated. Generally, for some types of systems, if a fluid moving at supersonic velocities is directed against a suitable wedge-shaped flow deflector, a single step normal" shock wave will be generated as evidence that the fluid stream is moving at supersonic speed. The Schlieren system may be used to indicate the existence of such a shock wave, the angle of this shock wave relative to the angle of a knife edge shaped flow deflector used to generate the shock wave, and the the Mach number velocity of the air stream exhausting from the nozzle as a function of the shock wave angle.

Turning to FIGS. 4 to 7, photographs are set forth which were obtained from a Schlieren mirror system. The photographs characterize the air entry ports of this invention having diverging cross-sections at their exhaust end compared with the constant cross-section air entry ports of the prior art. The Schlieren photographs give evidence that at applied process air pressures of between 140 pounds per square inch gauge and I pounds per square inch gauge, air ports with a 0.020 inch diameter throat and a 0.04l inch diameter exhaust end, the jetstream issuing from the end of the nozzle is flowing at supersonic velocity and that this flow is being compressed from supersonic to subsonic velocities through a series of complex patterns of shocks interacting with the boundary layer. The Schlieren image further shows that the jetstream leaving the nozzle is not being compressed from supersonic to subsonic velocity through a single normal shock wave; apparently because the interaction between the shock wave and the Diameter 01 air entry p'irt Process air flow at various applied air pressures Throat, Exhaust inches endfinehvs Press, (p.s.i.g.) 00

0.020 0.041 Flow, S.C.F.M 1.0 1 2 1.8 1.4 1.4 1.4 1.4 1.4 1.4 0.020 0.026 ..do 1.0 1.2 1.3 1.4 1.4 1.4 1.4 1.4 1.4 0.016 0 031 .do 0.5 0.7 0.0 0.0 0.9 0.0 0.0 1.0 1.0 0.016 0021 do (.5 0.0 0.7 07 0.8 0.8 0.3 0.8 .8

Length of diverging section is 3.33 times diameter of exhaust end.

boundary layer is not a single step. When the nozzle is operated at pressures ranging from 140 pounds per square inch gauge to l60 pounds per square inch gauge applied process air pressure, the Schlieren image revealed that a series of very small, oblique standing shock waves is generated by the jetstream (leaving the diverging end of a supersonic fluid conduit which had a throat of 0.020 inches diameter and a maximum divergent diameter of 0.041 inches) which clearly assumed the form of a small translucent bayonet. The bayonet-shaped jetstream was criss-crossed with a pattern of alternating dark-toned diamond shaped, and light-toned X-shaped forms. Overall length of the bayonet may be between one-eighth inch to threeeighths inch at air pressures of 140 to 160 pounds per square inch gauge, respectively.

The light-toned areas on the Schlieren image are points of relatively low air density, whereas the darktoned areas are points of relatively high air density. Since shock waves are essentially planes of high compression, air density is relatively high in a shock wave plane and in FIGS. 3 to 7 show up as dark areas in the Schlieren image. This is an important distinction, because in view of the Schlieren image of the jetstream issuing from the supersonic nozzle which is operated at 160 pounds per square inch gauge process air pressure, and which features a 0.020 inch diameter throat diverging to an 0.04] inch diameter at the exhaust end of the nozzle (the length of the diverging section being 3.33 times the diameter of the exhaust end of the nozzle as per FIGS. 4 and 6, close examination shows clearly that a light-toned area is present immediately downstream of the nozzle. This indicates that the air is traveling at supersonic velocity at the exhaust end of the nozzle because if it were traveling at sonic velocity, it would shock out immediately downstream of the nozzle and a dark (rather that a light)-toned spot would appear at this point in a Schlieren image of the jetstream leaving the nozzle.

If the internal cross-section of the nozzle were of constant cross-section along its length instead of divergent at the fluid exhaust end of the nozzle, then this constant diameter cross-section conduit would constitute the throat of a sonic velocity fluid flow nozzle. Under these conditions, compressible fluid flow theory predicts that an air stream which achieved sonic velocity in this constant diameter throat would be expected to shock out as it left the nozzle and form a shock wave immediately downstream of the nozzle. The Schlieren image ofajet stream issuing from such a nozzle should then show a dark spot (representing a shock wave) immediately downstream of the nozzle. FIGS. 5 and 7 show the Schlieren image of a jetstream issuing from a nozzle of constant diameter (0.032 inch) crosssection, and reveals that a dark spot representing a point of air compression (i.e., a shock wave) is definitely present immediately downstream of the nozzle exhaust.

Having thus disclosed the invention, what is claimed is:

l. A fluid yarn processing jet comprising a body member having a passage extending along a straight axis therethrough and through which yarn passes for treatment, at least one conduit into the passage for di recting fluid at high velocities against the yarn said conduit being flared at the point ofjuncture with said passage.

2. The apparatus of claim 1 wherein two conduits are employed on opposite sides of said passage.

3. The apparatus of claim 1 wherein said passage and said fluid conduit have circular cross-sections.

4. The apparatus of claim 1 wherein said conduit lies in a place perpendicular to the longitudinal axis of said passage.

5. The apparatus of claim 1 wherein said conduit is radial to said passage.

6. The apparatus of claim 1 wherein a yarn stringup slot runs the length of said passage and is radial thereto.

7. A fluid yarn processing jet comprising a body member having a passage extending along a straight axis therethrough and through which yarn passes for treatment, at least one orifice tapped into said passage, said orifice being suitable for receiving a conduit for directing fluid against the yarn, said conduit being flared at the point of juncture with said passage.

8. The apparatus of claim 7 wherein two conduits are employed on opposite sides of said passage.

9. The apparatus of claim 7 wherein said passage and said fluid conduit have circular cross-sections.

10. The apparatus of claim 7 wherein said conduit lies in a plane perpendicular to the longitudinal axis of said passage. 

1. A fluid yarn processing jet comprising a body member having a passage extending along a straight axis therethrough and through which yarn passes for treatment, at least one conduit into the passage for directing fluid at high velocities against the yarn said conduit being flared at the point of juncture with said passage.
 2. The apparatus of claim 1 wherein two conduits are employed on opposite sides of said passage.
 3. The apparatus of claim 1 wherein said passage and said fluid conduit have circular cross-sections.
 4. The apparatus of claim 1 wherein said conduit lies in a place perpendicular to the longitudinal axis of said passage.
 5. The apparatus of claim 1 wherein said conduit is radial to said passage.
 6. The apparatus of claim 1 wherein a yarn stringup slot runs the length of said passage and is radial thereto.
 7. A fluid yarn processing jet comprising a body member having a passage extending along a straight axis therethrough and through which yarn passes for treatment, at least one orifice tapped into said passage, said orifice being suitable for receiving a conduit for directing fluid against the yarn, said conduit being flared at the point of juncture with said passage.
 8. The apparatus of claim 7 wherein two conduits are employed on opposite sides of said passage.
 9. The apparatus of claim 7 wherein said passage and said fluid conduit have circular cross-sections.
 10. The apparatus of claim 7 wherein said conduit lies in a plane perpendicular to the longitudinal axis of said passage. 